Constant current air stratifier



May 20, 1958 L. G. MQLEAN 2,335,338

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I I I I CONSTANT CURRENT AIR STRATIFIER May 20,-1958 Filed May 17, 1956 May 20, 1958 L. G. MOLEAN CONSTANTCURRENT AIR STRATIFIER 4 Sheets-Sheet 3 Filed May 1'7, 1956 INVENTOR.

42 LYLE c5. MLEAN J l BY May 20, 1958 G. M LEAN 2,335,388

CONSTANT CURRENT AIR STRATIFIER Filed May 17, 1956 4 Sheets-Sheet 4 w on R 2 m United States Patent 2,835,388 CONSTANT CURRENT AIR STRATIFIER Lyle G. McLean, Warden, Wash.

Application May 17, 1956, Serial No. 585,432

' SClaims. Cl. 209-474 This invention relates to improvements in driers, classifiers and separators and more particularly to such ap paratus employing air flotation and stratification of the materials to be dried or separated.

The primary object of the present invention is to provide an apparatus adapted to remove heavier materials from lighter materials while the materials are in a continuous movement of flotation.

t A further object of the invention is to provide mean for removing heavier materials from lighter materials in a predetermined strata.

Another object of the invention is to provide means of moving the materials over controlled air currents by way of wipers associated with adjustable discharge openings through the side of the conveyor while the conveyor is in movement and discharging the heavier materials from under the lighter materials, all materials existing under a fluidized condition. I

A still further object of the invention is to provide an apparatus that can be extended to any length with any multiple of air chambers or ducts, depending upon the materials being processed.

Still another object of the invention is to provide air chambers or ducts having maximum efficiency and uniform cross-sectional area and blending from a round entrance end to a rectangular discharge end whereby the air chambers .or ducts can be placed side-by-side to form the bottom of a perforated conveyor bed.

It is a still further object of the invention to provide an apparatus of the present type having simplicity of design, economy of construction and efficiency in operation.

The novel features that are considered characteristic of the invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of specific embodiments when read in connection with the accompanying drawings, wherein like reference characters indicate like parts through the several figures and in which:

Figure 1 is a side view in elevation of a drier, classifier and separator apparatus in accordance with the present invention, parts being broken away for convenience of illustration;

Figure 2 is a cross-sectional view, taken on line 2-2 of Figure l;

Figure 3 is an enlarged fragmentary cross-sectional view, taken on line 33 of Figures 2 and 4;

Figure 4 is a plan view of the apparatus shown 'in Figure 1, the upper run of the conveyor chain having been removed and parts being broken away for convenience of illustration;

Figure Sis an enlarged fragmentary plan view, as seen from the plane of line 5-5 of Figure 1;

V Figure 6 is a fragmentary cross-sectional View taken on line 6-6 of Figure 5;

Figure 7 is a view in perspective of one of the conveyor shield assemblies;

Figure 8 is a view in perspective of one of the air ducts employed for delivering air up through the screen of the machine for drying and separating purposes;

Figure 9 is an enlarged fragmentary plan view of a plurality of assembled air ducts;

Figure 10 is a cross-sectional view taken on line 1010 of Figure 9;

Figure l'fis a side view in elevation of an air duct incorporating a heating unit, part of the Wall of the duct being broken away to show the heating unit;

Figure 12 is a fragmentary plan View of one side of the conveyor shield elements;

Figure 13 is a fragmentary plan view of one side of the apparatus including a modified construction wherein the discharging of the materials is controlled by an adjustable retaining wall;

Figure 14 is an enlarged fragmentary cross-sectional view taken on line 14-14 of Figures 13 and 15, and Figure 15 is a cross-sectional view taken on line 15- 15 of Figure 14.

Referring now in detail to the drawings, specifically to Figs. 1, 2 and 4, a drier, classifier and separator, in accordance with the present invention, comprises a frame F supporting an endless conveyor C in cooperative relation with and above a material supporting bed B with a series of air ducts A disposed beneath the bed B and a series of discharge chutes D, preferably respectively associated with the air ducts A and supported laterally of the bed B. The framework F includes vertical legs 15, horizontal side frames 16 and 16A, cross end members 17', longitudinal members 1613 supported by the end members 17, and a base frame 18.

The air ducts A have rectangular upper ends 31, including opposed side walls 32 and 33, and cylindrical or circular lower ends 35, as shown in Figures 1, 2 and 7-9. Secured to the side walls 33 are reenforcing bars 34 which are level with the upper edges of the ducts A. The walls 32 of the ducts are spaced at their upper ends a distance equal to the diameter of the lower end 35 and extend straight down vertically along their center lines 36, while the side walls 33 are longer and spaced more closely than the side walls 32 and flare outwardly and downwardly at 37, blending into the cylindrical lower end 35.

T he dimensions and foregoing arrangement of the duct walls is such as to provide a cross-sectional area of uniform or constant size throughout the length of the ducts. It has been found that air pressure can be delivered by the duct most efiiciently where the size of cross-sectional area remains constant from the inlet to the discharge ends of the duct. A cylindrical intake is preferred to obtain maximum efliciency from a fan 59 which is disposed in the lower end 3501; each duct. Moreover, it is desirable to have a rectangular outlet to facilitate the assembly of any selected number of air ducts A in side-by-side relation throughout the length of the apparatus, depending upon the size thereof. If desired, an electric heating element 38 may be disposed across the ducts, as shown in Figure 11, to assist in a drying operation.

The bed B, as best shown in Figures 2 and 6, comprises a screen 30 which is mounted on the longitudinal frame members 163 and the air ducts A are supported between these frame members 1613. The rectangular upper ends 31 of the ducts A are assembled adjacent one another with their side walls 32 secured together and their side walls 33 and reenforcing bars 34 bolted to the respective inner sides of the frame members 1613'. In assembly, the top edges of the ducts A and reenforcing bars 34 are disposed above the upper surface of the frame members 16B and the screen 30 is stretched across the top edges of the ducts and the edges of the screen 30 is formed downwardly over the upper edges of the bars 34 and clamped to the frame members 168 by hold down bars 39 which are secured to the frames 16B by suitable fastening means, such as screws 4%. The spacing of the top edges of the ducts and bars 34 above the frames 16B is suflicient to dispose the upper surface of the body of the screen 30 level with the upper surfaces of the clamp bars 39 to provide a level surface over which materials can be moved. I

The conveyor C comprises a pair of spaced endless chains 20 trained over sprockets 21 and 2-:- respectively carried by shafts 22 and 25 which are journaled in saitable bearings 23 and 26 at opposite ends of the frame F with the lower runs of the chains spaced above the bed B. One of the shafts, in this case the shaft 22, is driven as by a chain 28 from a reduction gear unit 27 which may be driven by any suitable source of power, such as an electric motor 29. The speed that the conveyor is driven is a relatively slow speed in a constant direction, as indicated by the arrows in Figure l. Conveyor elements 41 are carried by and between the chains 21) for cooperation with the bed B and discharge chutes D.

The conveyor elements 41 are adapted for movement over the upper surface of the screen 30 and these ele* ments comprise end shields 42 secured to the links of the chains 20, as best illustrated in Figures 1, 2, 3 and 7. The bottom edges 43 of the shields are operatively positioned adjacent the upper surface of the screen 39 with a slight clearance and are properly positioned by the lower runs of the chains 20 operating on guideways 44 supported by brackets 46 mounted on the frame side members 16A. The upper runs of the chains also operate on guideways 45 which are supported by brackets d6 mounted on the frame side members 16.

The shields 42 are each provided with an opening 43' which intercepts the bottom edge 43 and a gate 47 operating in guideways 4-8 is adjustable up and down over the opening 43' and retained in desired position by a set screw 49 in one of the guideways 4-8. V-shaped wiper blades 50 extend between and are fixedly secured to each opposed pair of shields 42 with the ends 51 of the blades 50 extending through the openings 43 and beyond the respective shields 42. The ends 51 are secured, as by angle brackets 52, to the shields 42 adjacent the rear edges of the openings 43 with the bottom edges of the bars 50 contiguous with the bottom edges 43 of the shields.

Each pair of shields 42 is further braced and connected by a spacer bar 53 and a vertical brace 54 may connect the apex 55 of the wipers 50 with the spacer bar 53. The forward edges 56 of the shields 42 are offset to overlap the rear edges 57 of adjacent shields for maintaining alignment of said shields and forming side walls for the bed B during operation. The upper corners 58 of the shields are cut at an angle so that the shields can travel around the sprockets 21 and 22 without interference with one another.

The fans 59, within the bottoms of the ducts A, are respectively keyed to vertical shafts 60 which are journaled within suitable bearings 61 forming part of pillow blocks 62, as shown in Figures 1 and 2. The pillow blocks 62 are in turn bolted to the base frame 18 and journal a shaft 65 extending longitudinally of the frame. Mounted on the base frame is a variable speed changer unit 63 which is driven by a motor 64 and, in turn, drives the shaft 65. Bevel gears 66 are keyed to the shaft 65 adjacent each block 62 while bevel gears 67 are keyed to the fan shafts 60 and are in mesh with the gears 66, respectively. Obviously, other drive systems may be employed, but the described arrangement has been found very efficient. The speed changer 63 is preferred to enable variation of the speed of the fans for different ve- 4 locity of air delivery depending upon the materials being processed.

In order to deliver the most efiicient air stream, the lower edge of each duct A is turned inwardly to provide a flange 68 for preventing a back draft, and a ventura nozzle 69 is provided above the fan 59 and through which the air is forced, as best shown in Figure 10. The antiback-draft lower flange 68 has been found to be most important for preventing air from backing away from the fan due to centrifugal force and to the resistance to the flow of air up through the screen bottom 30 and the material thereon. Consequently, means must be provided at the entrance of the duct and on the inlet side of the fan for'maintaining the air in a constant forward movement through the duct against the back pressure offered from above. Preferably, the air flow is guided in a straight stream by an egg-crate bafile unit 70 spanning each duct A.

The discharge chutes D are disposed on each side of the bed 13 and preferably comprise an upper portion 71 having vertical walls and an inclined and tapered chute portion 72. The upper portion is rectangular in crosssection and the outer wall thereof extends muchhigher than the inner wall, the top portion of the outer wall being secured to the inner side of the longitudinal side frame member 16A while the inner wall is secured to the outer side of the longitudinal frame member 168 with the upper edge of the inner wall being no higher than the top of the member 1613 and the upper surface of the clamp bar 39. The lower chute portion 72 is inclined downwardly and laterally with its discharge end disposed beyond the side of the frame F. The chutes D are preferably mounted on the frame F in pairs, one on each side of the frame, and conveniently, they may be the same length as the ducts A with a pair of chutes D laterally contiguous with each duct A.

The intake end 73 of the bed B extends beyond the frame F and conveyor C at its intake end, and the discharge end 74 also extends beyond the frame F and conveyor C and terminates in a delivery chute having an adjustable end gate 74A for governing the depth of the materials being discharged through the chute. A supply chute 75, indicated by broken lines in Figure l is positioned at the receiving end of the bed B. The materials M to be separated is shown in Figure 6 as being stratified by flotation into stratas of course materials 76 and finer materials 77, the separate stratas being defined approximately along line 78. The gates 47 are adjusted so that their lower edges substantially coincide with the line 78 so the coarse materials in the strata 76 can be discharged through the openings 43' into the chutes 72 both by flotation and by the action of the wipers 50 and their ends 51.

Referring to Figures 13, 14 and 15, a modification is illustrated of the shields 42 wherein the discharge of the material through their openings may be predetermined and controlled by an adjustable retaining wall 79 disposed along the outer sides of the shields 42. This retaining wall 79 comprises a base 80 which is adapted to be bolted to the upper surface of the clamp bar 39. In this particular arrangement, the clamp bar is preferably supported at an inclination by the side frame member 16 so that the materials can drop by gravity from the ends 51 of the wiper blades 50', because in this embodiment, the ends 51' of the wiper blades terminate flush with the shields 42' in order to clear the retaining wall 79. In this embodiment, the gates 47 are mounted on the inside of the shields 42 so that the outside of the shields will be smooth and move flush along the retaining wall 79.

The retaining wall 79 is secured to the hold down bar 39 and the side frame member 16 by bolts 81 which pass through the slots 82 in the base 80 of the retaining wall 79. The end 83 of the retaining wall 79 may be adjusted along the side of the conveyor C to any desired location, allowing the materials being handled to be discharged at any desired point along the conveyor, dependingon the kind of materials being separated. The opposite end 84 of the retaining wall can extend beyond the machine, or this retaining wall may be provided in sections which may be added in alignment or removed in accordance with the lengthening or shortening of the conveyor C and bed B.

In the operation of this new and improved drier, classifier and separator, some kinds of materials can be separated by adjusting the gates 47 over the openings 43 of the shields 42 to the desired opening, and as the materials are fed along over the screen 30 from the feed end of the conveyor, air is directed up through the ducts A to stratify the materials so that as the wipers 50 travel over the screen 30, the coarser materials 76 will be discharged out through the openings 43' into the receiving chutes 72. The coarser materials are discharged into the first of the chutes, while the finer materials travel further along the conveyor and are discharged into the chutes farther along the bed, the materials becoming finer and finer as the material progresses along the bed. The real fine materials pass over the tail gate 74A and are discharged out through the chute 74. Only a few air ducts A and discharge chutes D have been shown, but any number of chutes can be provided for grading the materials in various grades.

Referring to Figures 13, 14 and 15, the retaining walls 79 are provided for determining the point at which the materials can be discharged by the conveyor C from the bed B into the receiving chutes D by adjusting the ends 83 of the retaining walls along the sides of the conveyor. This discharge point can be selectively determined according to the kind of materials being separated.

From the foregoing description, it can be understood how materials can be stratified by air flotation and separated by controlling the amount of air forced up through the materials and by controlling the depth of the openings under the gates 47 and the point in the travel of the materials to their discharge into the receiving chutes. Further, the height of the discharge tail gate 74A can be adjusted to effect the separation of the materials by controlling the depth of the materials flowing through the conveyor.

Although certain specific embodiments of the invention have been shown and described, it is obvious that many modifications thereof are possible. The invention, therefore, is not to be restricted except insofar as is necessitated by the prior art and by the spirit of the appended claims.

What I claim is:

1. A separator or drier apparatus comprising a frame, a bed on said frame and having a foraminous portion, a series of aligned air ducts mounted on said frame beneath the foraminous portion' of said bed, means for inducing an air stream upwardly through said ducts and the foraminous portion of said bed to dry or stratify by flotation materials on said bed, a series of aligned discharge chutes on said frame and adjacent at least one side of said bed, and an endless conveyor mounted on said frame longitudinally above said bed for moving the stratified materials along said bed and discharging the lower strata ofthe materials from said bed into said chutes, said air ducts each comprising a duct open at both ends with one of said ends being circular and the other end being rectangular with the walls of the duct blending between said ends and defining a cross-sectional area of uniform size throughout the length of said duct, the center lines of two opposed sides of said duct being parallel to facilitate mounting of adjacent ducts in side-by-side relation.

2. An apparatus as set forth in claim 1 wherein the lower end of said duct is circular, said means for inducing an air stream comprising a fan disposed within the lower duct end, and a radially extending inturned flange on the lower end of said duct to preclude back-drafts from said fan.

3. An apparatus as set forth in claim 2 wherein said lower duct end is provided with an upwardly and inwardly inclined flange above said fan to produce a ventura effect.

4. A separator or drier apparatus comprising a frame, a bed on said frame and having a foraminous portion, a series of aligned air ducts mounted on said frame beneath the foraminous portion of said bed, means for inducing an air stream upwardly through said ducts and the foraminous portion of said bed to dry or stratify by flotation materials on said bed, a series of aligned discharge chutes on said frame and adjacent at least one side of said bed, and an endless conveyor mounted on said frame longitudinally above said bed for moving the stratified materials along said bed and discharging the lower strata of the materials from said bed into said chutes, said conveyor comprising conveyor units each including a pair of side shields spaced for movement along opposite sides of said bed and each having a discharge opening intercepting thebottom edge thereof, and a Wiper bar extending between said shields with the ends of said bar terminating adjacent the trailing edges of said openings.

5. An apparatus as set forth in claim 4 wherein said wiper bar is V-shaped with the branches thereof inclined rearwardly to direct materials laterally through said discharge openings.

6. An apparatus as set forth in claim 5 comprising a vertically movable gate on each shield for selectively regulating the upper edge of the discharge opening therein.

7. An apparatus as set forth in claim 6 wherein one of the side edges of each shield is offset to overlap the adjacent edge of the corresponding shield of an adjacent unit.

8. An apparatus as set forth in claim 7 comprising a baffle plate extending along at least a portion of each side of said bed and blocking the discharge openings in said shields.

References Cited in the-file of this patent UNITED STATES PATENTS 782,078 Stebbins Feb. 7, 1905 2,574,493 McLean Nov. 13, 1951 2,698,086 I Vogel Dec. 28, 1954 

